


the sluts of the london institute

by shoesoftennis



Category: The Infernal Devices Series - Cassandra Clare, The Shadowhunter Chronicles - All Media Types, The Shadowhunter Chronicles - Cassandra Clare
Genre: Canon Divergence, Crack, Crack ships everywhere, Everyone thinks mortmain is hot, Everything i didn't get from the books, F/M, Hot Mortmain, M/M, Multi, Not Beta Read, Parabatai, Polyamorous relationship, We Die Like Men, Young Mortmain, also jem takes the yin fen like someone snorting cocaine, automatons, it's just a thing, my friend hates me, shut up
Language: English
Status: In-Progress
Published: 2020-08-01
Updated: 2020-08-01
Packaged: 2021-03-05 21:21:53
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,073
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25652035
Author URL: https://archiveofourown.org/users/shoesoftennis/pseuds/shoesoftennis
Summary: Mortmain has bought up all of the yin fen. It all begins in the drawing room, and things go downhill from there. A trip to Woolsey's, a weird thing with the rain, a bit of soul searching, and then Mortmain. Hot young Mortmain who Tessa is going to go with a little too eagerly. Well, Jem can't have that, can he? Neither can Will. And they've all agreed that, well, maybe Mortmain isn't so bad. (Is it just because he's hot? Maybe. Shut up.)
Relationships: Jem Carstairs/Axel Mortmain, Jem Carstairs/Tessa Gray/Will Herondale, Tessa Gray/Axel Mortmain, Will Herondale/Axel Mortmain
Kudos: 4





	the sluts of the london institute

**Author's Note:**

> This is a crack fic that I started writing because I thought it was hilarious, and personally, I think it is lol. Don't expect much of this to be serious because it won't be. Also, there will probably be foursomes and threesomes and shit in later chapters. Okay, awesome. Enjoy!

The room was silent when Charlotte finished reading Mortmain’s letter. He still wanted Tessa, which was no surprise, but for him to hoard all the  _ yin fen _ —though not out of character—seemed deeply personal. Not to Mortmain but he wasn’t watching life leak out of Jem like a broken faucet. They were, and there wasn’t anything they could do about it. The letter gave no indication where Mortmain might be hiding, and even if they figured out a plan, it might be too late for Jem. He had never gone this long without the demon drug. Would it even slow his impending death after so long out of his system?

The packet Mortmain had sent with the letter taunted them all, filled with the thing they now depended on their nemesis for. None of them could bear to look at it, not even Will. His hands were at his sides now, clenched into white-knuckle fists.

Tessa was the one who broke the silence. “I’ll go,” she said. “Mortmain wants me. He always has, and now he’s dangling this over our heads like a sword. Our only choice is to let me go.”

“No!” Will burst out at the same time that Jem said,

“Absolutely not.”

“I’m not asking,” Tessa said, whirling on Jem. “You can’t forbid me from doing this.”

Jem’s face darkened. “I can because you’re endangering yourself for me. I won’t let you do that.”

“That’s ridiculous,” Tessa snapped. “You need  _ yin fen  _ to survive.”

“No, I need the drug to temper my curse,” Jem said. For once, he sounded on the verge of anger. “That’s not the same thing.”

“It might as well be,” hissed Will.

“We are not letting Tessa go!” Charlotte exclaimed. She stood so fast that her chair nearly tipped over. Her face had reddened like a ripe tomato, and her small hands clutched the letter like a lifeline. “Tessa, we will find another way.”

“How?” Tessa said. “We don’t even know where Mortmain is. Our only link to him are those numbers he gave us.”

Jem gripped Tessa’s hand, and she glanced down at him. His face was pinched with fear that sparkled at the edges of his eyes. “Tessa, if you go, you don’t know what he’ll do to you,” he said in a low voice.

A blush flickered over Tessa’s cheeks. She put a hand over her mouth and then shook her head. “I don’t,” she said, “but… well, at least he’s not…”

“What, a wrinkly old man?” said Will. “Yeah, at least he doesn’t look like Gabriel.”

Gabriel shot a glare at Will. “I’m not a wrinkly old man.”

Will held up his hands. “I’m just saying, if you put Mortmain and Gabriel side by side and asked me to pick which one I’d rather kiss, I’d pick Mortmain.”

“That’s because you hate me,” Gabriel said. “This has nothing to do with how handsome I am compared to Mortmain.”

“You’re right, it doesn’t because there’s no contest. On the scale of handsomeness on which I am a ten—the most handsome—Mortmain is an eight, and you are a negative one thousand.”

“Can we get back to the matter at hand?” said Charlotte. She looked pleadingly from Will to Gabriel and then back to Will.

Will returned her desperate gaze and silently conceded. He jabbed a finger at Tessa. “Right. Let’s get back to the matter at hand. Tessa, you are not allowed to fuck Mortmain, no matter if he is an eight.”

“Language, Will!” exclaimed Charlotte.

“I’m not going to fuck Mortmain!” Tessa cried.

“Language, Tessa!”

“Well, if you’ll excuse me, Charlotte,” Tessa began, her arms crossed over her chest as she narrowed her eyes at Will, “I do  _ have  _ womanly needs, you know, and it’s not fair for me to put them all on Jem when we’re not even married yet. Not to mention he hasn’t taken any  _ yin fen  _ for the past month.”

Jem’s mouth dropped into an  _ o _ . “You think I can’t perform without  _ yin fen _ ?”

“Oh, for Christ’s sake,” muttered Cecily, standing up and stalking towards the door. “I am not sitting here and listening to you three discuss your relationship problems. Seriously, Will, if Jem wasn’t your  _ parabatai _ , I would have suggested a  _ menage a trois  _ long ago.”

Charlotte pinched the bridge of her nose. “That’s it. That’s it,” she said. She smoothed out the letter on her desk. “Will, you and Tessa and Jem need to sort some things out, so when you’re ready to enter society as unfettered individuals, we will resume determining what needs to be done about Mortmain.” 

Charlotte, Gideon, Gabriel, and Cecily filed out, leaving the love triangle behind. When the door clicked shut, Will stuck his hands in his pockets. “Nobody wants a  _ menage a trois _ ,” he said. “Least of all me.”

“I’m hurt,” said Jem, a hint of humor trickling into his voice. “Pardon me, I must take my demon drug before I lapse into further sexual disrepair.”

Tessa sighed theatrically. “You’re not in sexual disrepair,” she said.

“Yeah. You’re not. Look, if I liked men, you’d be the first person I’d take to bed, Jem,” Will said.

“Is that so?” said Jem, glancing up at his  _ parabatai  _ with a smile. 

“Rightly.”

Rolling her eyes, Tessa stalked over to Charlotte’s desk and grabbed the packet of  _ yin fen _ . Remnants of silvery powder coated her palm and itched in between her fingers. She brought it back to Jem, handing it to him. “I know you don’t want me to, but I will turn myself into Mortmain. I won’t regret doing it, if it’ll save you,” she said gently.

Jem shook his head firmly. “No, we will not allow Mortmain to have you,” he said. “We don’t know what he has planned for you, and I vote we never find out.”

“This is not a democracy,” Tessa said. “Especially where your health is concerned.”

“Exactly,” said Will. He placed a hand on Jem’s shoulder, and Jem squeezed it. “Maybe Tessa can lend me her warlock powers and I can pretend to be her.”

“ _ No one  _ is falling into Mortmain’s clutches,” Jem said.

“Is ‘clutches’ really the right word? Probably more like tender embrace.”

Jem rubbed his temples, looking worse off now than when they had started arguing. He looked at the packet on his lap. “If you want to get railed by Mortmain, Will, just come out and say it. We’ve had our suspicions about you and Woolsey Scott and Magnus Bane, you know,” he said.

“Now  _ that’s  _ an interesting  _ menage a trois _ ,” Tessa murmured.

“Okay, the more we say those words, the less they sound like actual words,” Will said.

Jem tapped a hand on the arm of his chair. “We should talk to Magnus Bane,” he said. He stood then, leaning heavily on his cane.

“No, you’re not going anywhere until you take the  _ yin fen _ ,” Will snapped, “and I have never in my life fucked either Woolsey Scott or Magnus.”

“Ooh, first name basis,” Jem said, a smirk tipping up his papery thin lips. 

Will cut him a sharp glare and shoved the packet of drugs into Jem’s hand. “Take it,” he said.

“I wonder if Magnus would agree that Mortmain is… attractive. I think he would,” Tessa mused. “After all, he probably prefers to switch positions in bed with his lovers, don’t you think? I wouldn’t peg him as a bottom.”

“Magnus? No. Verse all the way,” Jem answered. He snorted the  _ yin fen  _ like cocaine, and it left a ring of silver around his nostril. He wiped it away with his sleeve. Already, color was seeping into his cheeks like a river feeding an ocean, and Tessa breathed a relieved sigh. That would tide him over for the moment. Hopefully long enough that they could take a trip to Woolsey’s house and sort out this whole argument with Magnus’ coveted opinion. Woolsey, of course, would feel the need to weigh in, but everybody silently decided the werewolf’s opinion mattered much less than the worldly warlock’s. 

***

Woolsey’s hair looked like it had been struck by lightning. He opened the door with angry gusto, his eyes a bit wild even for a werewolf. He had no shirt, and his pants were unzipped, the hem hanging low on his slender hips. “What in fuck do all  _ three  _ of you want? It was bad enough when  _ one  _ of you was knocking down our door about some stupid curse,” Woolsey said. He glared pointedly at Will who had the good grace to look sheepish.

“We are very sorry to interrupt you,” said Jem, “but we have to ask Magnus’ opinion on a very important matter. He is here, isn’t he?”

Jem’s eyes traveled over Woolsey, one eyebrow quirked. He already knew the answer to his own question.

The werewolf’s eyes narrowed. “What if I say no?” he said.

“Woolsey darling, no need to fight with the Nephilim,” Magnus said. He ducked under Woolsey’s arm, but he didn’t look pleased to see them either. “My opinion comes highly recommended on most things. If you ask your question quickly, I would be happy to give it free of charge. This time.”

“Of course you would,” muttered Woolsey. “Just as things were getting good.”

“What things?” asked Will.

Jem hid a grin behind his hand. “Wouldn’t you like to know?” he said.

Woolsey rolled his eyes and opened the door wide enough for them to come in. They followed Woolsey and Magnus into the sitting room. Jem and Tessa settled on the couch with Will seated on the armchair next to Jem. 

Magnus disappeared for a moment, and when he returned, he was wrapping a red velvet robe about himself. He perched himself on the loveseat, one leg crossed over the other. Woolsey took up a spot by the mantle, leaning on it and crossing his arms over his chest. “So,” Magnus began, “what is it that you wanted to ask me?”

With a courteous smile, Jem said, “You have seen Mortmain before, haven’t you?”

Magnus raised a manicured eyebrow. “Yes, of course,” he said. “He’s quite a handsome young man. I didn’t expect that. I honestly expected a middle-aged man verging on mania, and I was shocked to see mania wear such a pleasant face.”

Jem, Tessa, and Will all nodded in agreement. Mortmain had some childhood issues (caused by Shadowhunters, of course.) They couldn’t blame him for wanting revenge on the racist, classist, elitist Shadowhunters who perpetually killed innocent mundanes and Downworlders. Could they blame him for showing up with horrible machines that tried to hack off their heads even though none of them had had anything to do with the death of his parents? Could they blame him for trying to kidnap and forcefully marry Tessa? Yes, yes, they could. However, as Magnus had put it, his handsome face made up for many of his villainous tendencies.

“His end goal is probably good,” muttered Will. 

All eyes turned on him. 

He shrugged as if unseating the weight of their stares. “What? Nobody should have murdered his parents,” he said, “but he stole all the  _ yin fen _ and made this so damn personal. He didn’t have to. And why us? Besides the fact that we rescued Tessa.”

“Good intentions, bad actions,” said Jem. 

“I’d say questionable intentions,” Magnus chimed in. “Nothing’s so black and white as ‘good and bad.’”

Woolsey snorted. He pushed off the mantle and hung over the back of Magnus’ chair, wrapping his arms around his warlock boyfriend. “You Shadowhunters are the fucking worst, though,” he said. “Completely bad. No gray area to fret about.”

They left Woolsey’s house in neutral spirits. Nothing seemed decided, even though they had received the answer they had come to attain. They took the carriage through the city, the silence between all three thick as morning fog. Streetlamps lit the cobblestones a lazy yellow, and at some point, it began to rain, mud bubbling up from the storm drains. When they reached the Institute, Will opened the carriage door before Cyril could. Rain drenched his dark hair immediately, and his clothes clung to his muscular frame. Jem and Tessa both stared at him, and Will flashed them a grin. “Come on out, the weather’s fine,” he said.

Cyril appeared beside Will. He glanced into the carriage at Jem and Tessa who just stared back. “What are you doing?” Jem said. “You’re going to freeze.”

“Maybe then Tessa will look at me like I’m Mortmain,” he said. 

Jem rolled his eyes and then smiled too, stepping out into the rain. His clothes soaked through immediately, sticking to his thin body. “You know, I feel quite refreshed,” Jem said, “but, Will, why are we doing this? Other than eliciting certain sinful feelings in Miss Tessa.”

“Oh my God,” Tessa said. “You both are desperate, and the look does not fit either of you.”

Will and Jem shared another smile. Jem stepped forward, offering one hand to Tessa, and said to Cyril without looking at him, “Please take the horses to the stable, Cyril, and make sure they’re fed and dry.”

“Yessir,” said Cyril, puzzled but relieved that he could get out of the rain. “Course, sir.”

“Thank you,” Jem said. He curled his fingers then uncurled them, giving Tessa a gentle smile. “Come along if you’re not too shocked by our uncouth states.”

“Not at all,” said Tessa. She offered him a small smile back, simply a twitch of her lips. She took his hand, squeezed it once, and stepped from the carriage. Freezing droplets slipped beneath the collar of her dress, sliding down her spine and into the crevice of her breasts. Her petticoats dripped, heavy like manacles around her ankles, when they dipped into the puddle beneath the carriage steps. Sophie would have a cow when she saw the muddy hem, but at the moment, Tessa did not care.

Will placed his hands on his hips, rivulets dripping down his face like tears. Why were they doing this? What kind of literary metaphor could Tessa apply? She glanced from Will to Jem then shook her head. “We should go inside,” she said, “before we all catch cold. We should consider commissioning a few umbrellas for the carriage as well.”

“Petition Charlotte,” Will said as they climbed the steps to the Institute. 

“No, please, let me petition the pope,” Tessa said.

Jem let out a soft musical chuckle. It chimed through the courtyard, almost like vibrato from his violin. Warmth bubbled up in Tessa’s chest. Being with these two, however hairbrained they made each other, gave her a feeling she couldn’t name. Was it love? Could she really, truly love two people at once? The thought seemed like a betrayal of what she had always been taught in fairytales and religion, of monogamous soulmates. Adding another person felt selfish, but how could it be when she loved them both so? 

Will opened his mouth to reply, but all that came out was a screeching creak. His eyes widened. Jem’s shoulders went rigid, and his sword flashed out from his cane. Tessa stared at the blade, and the reflection in it sent shivers down her flesh. “Oh my God,” she murmured.

Automatons flanked the steps. Their metal bodies gleamed with rain and gauzy moonlight, their feet submerged in mud, their faces smooth and without eyes or anything to make them look remotely humanoid. Sabers and saws and shotgun barrels replaced their arms below the elbow, glistening like edges of nightmares vivid enough to have been real. Tessa turned around slowly as if the speed of her movement would hide her, but the man in the middle of the automatons met her eyes. 

Mortmain stood with his hands in his coat pockets. His mouth was tight, set into a neutral expression. Tessa squared her shoulders and narrowed her eyes.

“Hello. Quite late to come calling for me, isn’t it?” Will said. He shifted in front of Tessa, his seraph blade already drawn and blazing with heavenly fire. “You could have at least sent a note.”

Mortmain flicked his eyes to Will; his expression remained the same. “You know I am not here for you. Step aside,” he said, “unless you want to be torn to ribbons.”

“Ribbons? Can I request linguine or perhaps triangles?” Will said. Though his tone was light, his back muscles clenched beneath his damp clothes. Tessa wondered if she should be looking at him like this or anyone.

She peeked over Will’s shoulder and took in Mortmain. He had come prepared for the rain in a wicked coat, and though the hood was drawn back, he looked decidedly less wet than the rest of them. Shadows flickered around him like live creatures feeding off the depravity of his soul but oh, that  _ jawline _ . It looked sharper in the moonlight, and she longed to kiss it, which she should not. She had Will and Jem whom she loved dearly, but something about Mortmain stirred  _ feelings  _ inside her like the ones Jem had referenced moments ago. She hated how intense the heat boiling in her belly was. 

“Tell us what you want,” Tessa said, her voice ringing in the night’s stillness. 

Mortmain canted his head to the side. “Do I have to even answer that question?” he said. “You, Miss Tessa, are who I have personally come for since everyone I have sent has failed miserably.”

“You’ll fail too,” Will said, a bite to his voice.

With her chin held up high, Tessa stepped out from behind Will, putting her body between Mortmain’s automatons and her Jem and Will. “I’ll go,” she said. “If you promise, no, if you’ll  _ show  _ me that you’ll send your supply of  _ yin fen _ to Jem.”

“What!” Will cried out.

“No,” Jem hissed.

The pain in their voices ached, but Tessa did not acknowledge them. She would be all right. This was a sacrifice she was willing and able to make to keep those she loved safe. “Well?” she said to Mortmain.

He raised an eyebrow. “I have nothing to gain from keeping it,” he said. “Consider your request granted.”

“Thank you,” Tessa said. She started down the Institute stairs, but Jem blocked her path, his sword held out in front of him. 

“I will not let you take her,” he said. He sheathed his sword in his cane and smiled courteously, bowing. “Unless you take me as well.”


End file.
